Adding an ESXi host to an EVC enabled vSphere 6.7 Clusters fails with the following error message:
The host's CPU hardware does not support the cluster's current Enhanced vMotion Compatibility mode. The host CPU lacks features required by that mode.
See KB 1003212 for more information.
Host is of type: vendor intel family 0x6 model 0x8e
The target host does not support the virtual machine's current hardware requirements.
The cluster is running with EVC Mode "Haswell" and contains hosts with "Skylake" and "Kaby Lake G" CPUs while the new host has a "Kaby Lake" CPU. There is no reason why it shouldn't be possible to add the host to the cluster. All Hosts are running ESXi 6.7 U3 (Build 15018017).
As some missing features are introduced with recent security patches I suspected a microcode issue. However, the problem couldn't be solved with rebooting hosts or applying BIOS patches. After creating a new Cluster in "Haswell" mode, I was able to add the host to this Cluster, but not the old one, so the problem must be cluster related.
The solution was to disable EVC, add the Host to the Cluster and reenable EVC. Just make sure that no VMs are switched on while EVC is disabled.